[2] He had four half-brothers by his father's second wife, Margery la Zouche: Robert, Thomas, John and Brian.

[5] Hicks notes that the Willoughby family had a tradition of military service, but that the 5th Baron 'lived during an intermission in foreign war and served principally against the Welsh and northern rebels of Henry IV'.

Henry IV denied them trial by their peers, and Willoughby was among the commissioners[9] who sat in judgment on Scrope in his own hall at his manor of Bishopthorpe, some three miles south of York.

Scrope was beheaded under the walls of York before a great crowd on 8 June 1405, 'the first English prelate to suffer judicial execution'.

[16] A chapel in the church at Spilsby still contains the monuments and brasses of several early members of the Willoughby family, including the 5th baron and his first wife.